nIridosmium(Min) The native compound of iridium and osmium. It is found in flattened metallic grains of extreme hardness, and is often used for pointing gold pens.
Century Dictionary and Cyclopedia
niridosmiumA native alloy of the metals iridium and osmium, in different proportions, usually containing also some rhodium, ruthenium, platinum, etc. It crystallizes in the hexagonal system, has a tin-white to steel-gray color, and a specific gravity varying from 19.3 to 21, and is nearly as hard as quartz. It is found in minute flat scales with platinum in the Ural mountains, South America, and Australia, and also in northern California. Iridosmium is fusible with great difficulty, and resists all ordinary chemical reagents. It has a limited use for the pointing of gold pens. Also osmiridium.
Chambers's Twentieth Century Dictionary
nIridosmiuma native compound of iridium and osmium, used for pointing gold pens